1. Field of the Invention
The present invention relates to an apparatus for removing a deposited film at an edge portion of an object to be polished, and in particular relates to an apparatus for removing a deposited film at an edge portion of a device wafer having a circuit formed on the top surface thereof.
2. Description of the Related Art
A semiconductor wafer used as a substrate of a semiconductor device, for example, having no circuit formed thereon is called a bare wafer and is produced from a sliced ingot of a single crystal of silicon, etc., via processes such as chamfering, lapping, etching, annealing, and polishing.
The bare wafer is generally polished by a material manufacturer and there are various known polishing means disclosed in Japanese Unexamined Patent Application Publication No. 7-193030 and Japanese Unexamined Patent Application Publication No. 8-85051, for example.
On the other hand, a semiconductor wafer having a circuit formed thereon is called a device wafer and as means for removing an unnecessary deposited film by polishing it, such techniques disclosed as in Japanese Unexamined Patent Application Publication No. 10-312981 and Japanese Unexamined Patent Application Publication No. 2000-068273 are known.
In Japanese Unexamined Patent Application Publication No. 10-312981, it is shown that an excess metal film adhering to the outer circumferential fringe of a device wafer is polished and removed,by etching or making contact with a polishing pad. In Japanese Unexamined Patent Application Publication No. 2000-068273, it is disclosed that a film remaining in a portion having no pattern formed thereon in the outer circumferential fringe of a device wafer (a wafer edge portion) is removed by mechanically polishing it using a polishing pad rotated to be made contact with it.
However, in any one of the cases disclosed in the above-mentioned publications, a deposited film is removed along an extension line of a slope or a deposited film on a flat plane linking with a slope cannot be removed, so that the deposited film on the flat plane is prone to be peeled off during the transferring of the device wafer due to the contact with a chuck, for example, which may have a bad influence upon a post-process.
Furthermore, apparatuses capable of simultaneously removing a deposited film on the entire outer circumferential fringe, i.e., an end face, a slope, and a flat plane linking with the slope by a single polishing are demanded.
The present invention aims at solving the above-described conventional problems and further at responding to the demand, wherein deposited films on an end face, a slope, and a flat plane linking with the slope of the outer circumferential fringe of a device wafer can be simultaneously removed by a single polishing while peeling off due to a post-process, etc., which will generate a foreign substance, can be securely prevented by removing a deposited film on the flat plane. in an orthogonal direction thereto. Thereby, it is an object of the present invention to provide an apparatus for removing a deposited film being capable of completely suppressing a bad influence due to dusting and the like upon a post-process.
In order to achieve the above-described object, in accordance with the present invention, there is provided an apparatus for removing a deposited film in an edge portion of a substrate to be polished, the apparatus for removing the deposited film comprising: a polishing body having at least one polishing portion formed thereon and having substantially the same shape as that of the edge portion of the substrate; a forming body for forming the polishing portion having substantially the same shape as that of the edge portion of the substrate on the polishing body; a holding member for a forming body; a holding member for a polishing body; and a holding member for an object to be polished having mechanisms for rotation, horizontal movement, and pressing, wherein the forming body movably held by the holding member for a forming body is brought into contact with the polishing body held rotatably and vertically movably by the holding member for a polishing body so as to form the polishing portion, and wherein the substrate held by the holding member is urged into contact with the polishing body so as to remove a deposited film at the edge portion by polishing.
The polishing portion of the polishing body may be formed so as to substantially agree with an edge face, a slope, and a flat plane of the substrate to be polished. Preferably, the holding member for a forming body rotatably holding the forming body is capable of relatively approaching to and separating from the direction of the holding member for a polishing body while making an edge portion of the forming body in contact with the surface of the polishing body during the approaching. Further, the object to be polished may comprise the substrate and a deposited film formed on the surface of the substrate.
By adopting the means as described above in the present invention, an edge portion that is the external periphery of the device wafer is positioned at the polishing portion of the polishing body, so that deposited films on an edge face, a slope, and a flat plane linking to the slope of the edge portion can be simultaneously removed.
Even when the polishing portion wears down due to polishing, the most suitable shape can be maintained by correcting the polishing portion of the polishing body with the forming body. Then, the external periphery of the device wafer to be polished is positioned at the polishing portion and is relatively urged into contact with the polishing portion and rotating the device wafer, so that the edge portion of the device wafer can be polished in a sectional shape agreeing with that of the polishing portion of the polishing body, thereby simultaneously polishing the edge face, the slope, and the flat plane linking to the slope.